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Etiology of the membrane potential of rat white fat adipocytes

Bentley, Donna C.; Pulbutr, Pawitra; Chan, Sue; Smith, Paul A.

Authors

Donna C. Bentley

Pawitra Pulbutr

SUE CHAN sue.chan@nottingham.ac.uk
Associate Professor

PAUL SMITH paul.a.smith@nottingham.ac.uk
Assistant Professor



Abstract

The plasma membrane potential (Vm) is key to many physiological processes, however its ionic aetiology in white fat adipocytes is poorly characterised. To address this question, we have employed the perforated patch current-clamp and cell-attached patch-clamp methods in isolated primary white fat adipocytes and their cellular model: 3T3-L1. The resting Vm of primary and 3T3-L1 adipocytes were -32.1±1.2mV (n=95) and -28.8±1.2mV (n=87), respectively. Vm was independent of cell size and fat content. Elevation of extracellular [K+] to 50mM by equimolar substitution of bath Na+ did not affect Vm, whereas substitution of bath Na+ with the membrane impermeant cation N-methyl-D-glucamine+ hyperpolarized Vm by 16mV, data indicative of a non-selective cation permeability. Substitution of 133mM extracellular Cl- with gluconate, depolarised Vm to +5.5, whereas Cl- substitution with I- caused a -9mV hyperpolarization. Isoprenaline (10µM) but not insulin (100nM) significantly depolarized Vm. Single-channel ion activity was voltage independent; currents were indicative for Cl- with an inward slope conductance of 16±1.3pS (n=11) and a reversal potential close to the Cl- equilibrium potential: -29±1.6mV. Reduction of extracellular Cl- elevated the intracellular Ca2+ of adipocytes.
In conclusion, the Vm of white fat adipocyte is well described by the Goldman-Hodgkin-Katz equation with a predominant permeability to Cl-. Consequently, changes in serum Cl- homeostasis or the adipocyte’s permeability to this anion via drugs will affect its Vm, intracellular Ca2+ and ultimately its function and its role in metabolic control.

Citation

Bentley, D. C., Pulbutr, P., Chan, S., & Smith, P. A. (2014). Etiology of the membrane potential of rat white fat adipocytes. AJP - Endocrinology and Metabolism, 307(2), E161-E175. https://doi.org/10.1152/ajpendo.00446.2013

Journal Article Type Article
Acceptance Date May 20, 2014
Online Publication Date Jul 15, 2014
Publication Date Jul 15, 2014
Deposit Date Oct 19, 2016
Publicly Available Date Oct 19, 2016
Journal American Journal of Physiology-Endocrinology and Metabolism
Print ISSN 0193-1849
Electronic ISSN 1522-1555
Publisher American Physiological Society
Peer Reviewed Peer Reviewed
Volume 307
Issue 2
Pages E161-E175
DOI https://doi.org/10.1152/ajpendo.00446.2013
Public URL http://eprints.nottingham.ac.uk/id/eprint/37698
Publisher URL http://ajpendo.physiology.org/content/307/2/E161
Copyright Statement Copyright information regarding this work can be found at the following address: http://eprints.nottingh.../end_user_agreement.pdf

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf





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